Multi-term fractional diffusion-wave equation along with the homogeneous/non-homogeneous boundary conditions has been solved using the method of separation of variables. It is observed that, unlike in the one term case, solution of multi-term fractional diffusion-wave equation is not necessarily non-negative, and hence does not represent anomalous diffusion of any kind. © 2008 Elsevier Inc. All rights reserved.
Daftardar-Gejji, V., & Bhalekar, S. (2008). Boundary value problems for multi-term fractional differential equations. Journal of Mathematical Analysis and Applications, 345(2), 754–765. https://doi.org/10.1016/j.jmaa.2008.04.065